The goal of the Gene Expression and Bioinformatics Core (Core C) will be to provide expression arrays of muscle mRNAs to examine differential mRNA expression in various developmental states of unaffected individuals, muscle disease states and differences between stem cell populations at different stages of differentiation. The Core will also provide web-accessible annotation, cataloging facilities and state-of-the-art bioinformatics analyses. This will enable researchers from all Projects to maximally utilize the expression data sets to determine functional dependencies among the known genes and Expressed Sequence Tags (ESTs) and direct further biological validation of these putative dependencies. This critical biological validation step is described in each of the respective Project proposals. The facility will use two complementary microarray methodologies. The first methodology will be Affymetrix GeneChip arrays of human expressed sequences. The second will be the gridded array of normalized human muscle cDNA clones on microscope slides. The Aims of this Core are to 1) establish the web-based data portal, 2) standardize gene expression analysis technology, 3) develop benchmark data sets for gene expression in normal human muscle, and 4) use bioinformatics techniques to identify functional dependencies between interacting proteins.